The invention relates to rotatable cylindrical locks and more particularly to cylindrical locks having removable lock cores.
It is known to use cylindrical locks with various applications. Cylindrical locks have been used with furniture, automobiles, doors, and the like. The known cylindrical locks have been designed and constructed for these various applications and these designs are somewhat dependent on the particular application and the environment in which the lock is used.
In many applications using cylindrical locks the cylindrical locking mechanism is contained within the equipment. Once contained, only the key slot of the cylindrical locking mechanism is exposed. Because the cylindrical locking mechanism is contained, it is often difficult to repair the lock core within the cylindrical locking mechanism. Typically, it is often necessary to dismantle the equipment in order to gain access to repair the lock core. Similarly, if the user of the equipment desires to re-key the lock, it is necessary to dismantle the equipment in order to gain access to the lock core. Consequently, in these applications it is desired that the lock core be removable from the lock housing so that the lock core may be replaced, repaired or re-keyed.
It is further known in the art for cylindrical locking mechanisms to have removable lock cores. Cylindrical locking mechanisms of this nature are typically manufactured to have a groove that permits the lock core to rotate yet retains the lock core within the lock housing. Once the lock core is rotated to the unlocked position using the lock key, the lock core is released using a release key to manipulate the release tumbler such that the release tumbler will slidably engage the groove in the locking mechanism, thereby permitting the removal of the lock core. The release key is typically used only to remove the lock core and is not used to operate the lock. Exemplar cylindrical locks with removable cores are shown in U.S. Pat. Nos. 2,061,456 and 2,460,709.
Still further exemplar cylindrical locks with removable cores are disclosed in U.S. Pat. Nos. 4,398,405 and patent 4,416,129. Both of these patents use a special release tumbler that interacts with a special groove machined in the lock housing to release the lock core. During normal operation of the lock assembly, the special release tumbler interacts with a slot or groove in the cylinder to retain the lock core. The lock housing has a containment surface or inner surface that keeps the special release tumbler from being retracted in any position but the unlocked position. In both cases, the length of the release tumbler is greater than the diameter of the lock core so that it always protrudes from the lock core. One end of the special release tumbler is shaped such that it will fit through the special groove machined in the lock housing when the lock assembly is in the unlocked position and the special release tumbler is retracted using a release key or control key.
It will be understood and appreciated by those skilled in the art that with known locking mechanisms the lock housings have a groove manufactured in the housing to permit removal of the lock core. It will also be understood that a special tumbler must be employed, a tumbler different than the lock tumbler. These special manufacturing steps and additional parts add complexity and expense to the production of a cylindrical lock having a removable lock core.
An effort at overcoming these known problems is shown in U.S. Pat. No. 4,712,400. In that patent, there is shown a cylindrical lock having a removable lock core where the requirement for making a special groove in the lock housing, and the further requirement for a special release tumbler is eliminated. To this end, the lock housing is constructed with a tumbler block associated with a tumbler ledge formed on the interior surfaces of the cylindrical housing. The tumbler ledge extends inwardly a certain distance while the tumbler block extends inwardly for a slightly greater distance than the tumbler ledge. The tumbler ledge and tumbler block coact with a release tumbler located in the lock core. In this manner, the release tumbler will ride along and against a shoulder formed by the tumbler ledge and will be prevented from being actuated into its release position by the tumbler block. The tumbler block will prevent this actuation until the lock is manipulated to a certain position such that the release tumbler may be actuated by a release key and positioned out of blocking engagement with the tumbler block. The lock core is also constructed to include a block restrictor relief portion that permits 90xc2x0 of lock core rotation. The block restrictor relief portion coacts and accommodates the riding of the tumbler block therein during the normal rotational movement of the lock core. The block restrictor relief portion has a circumferential length greater than the circumferential length of the tumbler block, such that when the lock core is manipulated to the release position, the release tumbler may be actuated by the release key such that the release tumbler disengages with the tumbler block and extends into the block restrictor relief area of the lock core. Once in this position, the lock core may be removed from the lock housing.
Known problems exist with respect to the cylindrical locking mechanism shown in U.S. Pat. No. 4,712,400. As an example, the locking mechanism is limited to lock cores having only 90xc2x0 of rotation. Many current applications that require cylindrical locks also require lock cores that permit 180xc2x0 of rotation. As a result, there remains a need in the art to provide, among other things, a cylindrical locking mechanism having a removable lock core where the lock core may be rotated 180xc2x0 and where a special groove and tumblers are not required.
In an exemplary embodiment, the present invention is directed to a rotatable cylindrical lock assembly having a removable lock core with the lock core permitting 180xc2x0 of rotation. The cylindrical lock assembly of the present invention does not require the use of a special groove or tumbler. The rotatable lock assembly includes a lock housing, a lock core, an adapter, and a shifter. The lock housing has a cylindrical opening that receives and registers the lock core, adapter and shifter. Located within the cylindrical opening is a rotational slot that receives and engages the adapter. The adapter of the present invention includes a stop lug and a tumbler block. The stop lug is positioned in rotatable engagement with the rotational slot in the lock housing while the tumbler block is positioned in rotatable engagement with a block restrictor relief formed in the lock core. Once assembled, as the lock core is rotated from the locked position to the unlocked position, the lock core rotates freely until the edge of the tumbler block contacts the opposite side of the block restrictor relief. The adapter then moves clockwise along with the lock core until the stop lug contacts the opposite side of the rotational slot in the lock housing as the lock reaches the unlocked position. The total rotational movement of the lock core is 180xc2x0. In the unlocked position, the lock core is removable through the use of a release key.